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Q6. With reference to the circuit breaker for an a.c. generator A. Describe the preventive maintenance carried out on the circuit breaker for an A.C Generator. B. Explain the sequence of events that might occur if the breaker opens on a short circuit and state the check you would require following such event. C. Give a safe procedure to follow should a main circuit breaker fail to open under fault condition.

Q8. Explain how each of the following conditions contributes to the satisfactory performance of oil centrifuges. A. Correct bowl speed; B. Cleanliness of bowl; C. Low rate of feed to the bowl; D. Contaminated oil preheated prior to centrifuging; E. Contaminated oil allowed standing for an appreciable time prior to centrifuging.

Q6.(a) Suggest four reasons why the temperature of the oil in the steering gear system may  become excessive.

(b) With reference to steering gears explain how the ship may be steered in each of the following circumstances;

(i) destruction by fire of the primary supply cable;

(ii) destruction by fire of the telemotor lines;

(iii) bearing failure in the running pump;

Q3: State how safety is achieved with regard to gas emission in battery rooms where a large number of lead acid cells are stored with reference to - A. Provision of lighting; B. Ventilation if a fan is fitted; C. Type of distilled water container for topping up; D. Use of tools and replacement of defective batteries.

Q8. For vapour compression refrigeration machine, state how each of the following faults are indicated and how they are remedied:

(a) air in the system;

(b) Moisture in the system;

(c) undercharge;

(d) overcharge;

Q2. With reference to reciprocating air compressors explain the cause of the following faults.

A. Collapse of discharge valve springs;

B. Breakage of plate valves;

C. Overheating of the discharge air with an unrestricted air intake;

D. Inoperative piston rings.

Q7: Describe the routine maintenance required to be undertaken at periodical intervals, for inert gas system of a larger tanker

Q8: Sketch a safety valve of a type normally mounted on an auxiliary boiler. Identify with reasons those parts that require particularly close examination and attention during overhaul.  Describe how the valve is reset under steam after overhaul.

Q7. Recent experience has shown persistence damage occurring on seating faces of main engine exhaust valve, which is not confined to any particular unit; (a) State with reason the possible causes; (b) State the short-term action to be taken in order to minimize engine operational problem; (c) State with reason how future incident of this nature could be minimized